Modafinil is a drug generally used to treat excessive sleepiness caused by narcolepsy, obstructive sleep apnea/hypopnea syndrome (OSAHS) and shift work sleep disorder (SWSD). It is often described as a “wakefulness promoting agent” and is also prescribed for improving memory and mood. The drug and its uses were disclosed in already expired U.S. Pat. No. 4,177,290. Modafinil is marketed in the United States under the trade name PROVIGIL® in tablets comprising 100 mg and 200 mg modafinil.
The benzhydrylsulfinyl acetamide structure of modafinil makes it generally insoluble in water. One way to address the problem of insolubility is reducing the drug's particle size to increase the effective exposed surface area. U.S. Pat. No. RE 37,516 discloses improving solubility by a method of size reduction and a pharmaceutical composition that has at least about 95% of the modafinil particles having a diameter of less than about 200 μm and having a median size smaller than about 60 μm.
Another way to improve solubility includes surface treatment of drug particles using hydrophilic agents as disclosed in US application No. 20040253308 and WO application No. 2005004917.
Yet another way to improve solubility is disclosed in U.S. Pat. No. 7,115,281 which uses modafinil particles having bimodal size distributions. The size distribution is such that a proportion of the particles is smaller than about 41 um and a second proportion is greater than about 220 um.
Prior art approaches have focused so far on predominantly reducing particle size of modafinil.
There is an ongoing need to optimize the formulation and the methods used to prepare solid dosage forms of modafinil. Therefore, it would be desirable to provide a pharmaceutical formulation comprising modafinil particles having larger diameters made by a commercially feasible process, which is bioequivalent to PROVIGIL®.